Oncology/Hematology

Some Cancer Patients May Overdo Oral Meds

One in five cancer patients took oral drugs too often or in higher-than-prescribed doses, adding to evidence of potential "overadherence" with oral cancer medications, a prospective study showed.

Of 33 patients who were nonadherent to oral cancer therapy, 20 were overadherent and 13 were underadherent. The likelihood of overadherence increased with the complexity of a regimen or administration schedule, and breast cancer patients accounted for three-fourths of the overadherence, reported Sandra L. Spoelstra, PhD, RN, of Michigan State University in East Lansing, and colleagues online in the Clinical Journal of Oncology Nursing.

"Although not statistically significant because of lack of power, this study indicated that a relationship may exist between symptom severity and overadherence," the authors said in their summary.

"Patients may self-modulate doses after symptoms occur by not taking one or more doses, realize they are not following the prescribed regimen, and then double-up on doses after their symptoms resolve, leading to overadherence," they added. "As shown, more instances of overadherence were related with higher symptom severity at the exit interview."

The increased availability of oral chemotherapeutic or targeted drugs has increased the necessity for patient adherence to the prescribed regimen. A recent review documented problems with medication adherence among cancer patients. The study showed that underadherence -- taking less medication than prescribed -- occurred in 20% to 80% of cases.

Overadherence has been observed in several studies, but investigators performed little or no statistical analysis to characterize the issue, the authors said.

A recent study of symptom management in cancer patients provided additional evidence of overadherence to oral medications. Spoelstra and colleagues analyzed data from that study in an attempt to improve understanding about factors associated with overadherence.

The study involved 119 adult patients with various types of cancer treated with chemotherapy or targeted agents. As part of disease management, each patient received an informational tool kit that offered guidance in recognizing and treating side effects of therapy and sequelae of cancer.

The patients were randomized into three groups according to the type of follow-up employed. One group received eight weekly calls from an automated voice response system (AVR) that helped patients assess 15 possible symptoms. Patients with symptom severity ≥4 on a scale of 0 to 10 were referred to the tool kit.

The second group received calls from the automated system, as well as follow-up calls from advanced nurse practitioners to assist with severe symptoms. For the third group of patients, follow-up consisted of the AVR and calls from the nurse practitioners to manage medication adherence.

Investigators performed a final assessment at 10 weeks to evaluate symptoms, depression, and adherence. Spoelstra and colleagues also examined pharmacy and oncologist records to determine medication dose adjustments.

Overall, 42% of the patients were nonadherent, and the rate did not vary significantly among the three groups. The results showed that:

The number of missed doses increased with regimen complexity

Symptom severity declined over time in all groups

Higher rates of adherence were related to lower symptom severity

The authors conducted a more detailed assessment of overadherence, using pharmacy and medical records for 100 of the 119 patients. Caucasian women with breast cancer accounted for a majority of the patients in the analysis.

The authors found that 33 of the 100 patients were nonadherent to their oral cancer medications. Patients who were adherent, overadherent, or underadherent did not differ significantly with respect to age, sex, race, randomized intervention group, baseline symptom severity, or depression scores.

Investigators evaluated the patient adherence according to the complexity of their regimen (continuous treatment; 14 days on, 7 days off; 7 days on, 7 days off; and other). The 100 patients comprised 52 patients on simple regimens (same dose and frequency throughout treatment) and 48 on complex regimens (including alternating periods on and off medication and fluctuations in the prescribed dose).

Complex regimens included six patients on continuous therapy, 25 with 14 days on/7 off regimens, nine with 7 days on/7 off regimens, and eight with other types of regimens. The authors found a significant association between regimen complexity and adherence (P<0.01) and between cancer site and regimen complexity (P<0.01).

A preliminary analysis suggested that overadherence was associated with higher mean symptom scores. The authors found that as the number of episodes of overadherence increased, so did the number and/or severity of symptoms. In contrast, underadherent patients tended to report fewer and less severe symptoms.

"Oral agents can be attractive to patients because of the associated benefits in convenience, avoidance of visits to the clinic, and reduced impact on daily activities," the authors concluded. "However, these conveniences can lead to overadherence and potentially life-threatening toxicity.

Working from Houston, home to one of the world's largest medical complexes, Charles Bankhead has more than 20 years of experience as a medical writer and editor. His career began as a science and medical writer at an academic medical center. He later spent almost a decade as a writer and editor for Medical World News, one of the leading medical trade magazines of its era. His byline has appeared in medical publications that have included Cardio, Cosmetic Surgery Times, Dermatology Times, Diagnostic Imaging, Family Practice, Journal of the National Cancer Institute, Medscape, Oncology News International, Oncology Times, Ophthalmology Times, Patient Care, Renal and Urology News, The Medical Post, Urology Times, and the International Medical News Group newspapers. He has a BA in journalism and MA in mass communications, both from Texas Tech University.

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